Refactor search screen

[petervojtek]

from #215:

• the html template is completely different than the activity newsfeed html
• in code there are two different approaches how to handle the #hashtag click.. leader-content item details use some cached_hash_tags attribute provided by backend, while Post and UserPetition and activity newsfeed for all items (including leader content items) use another approach based on ng-click and event parsing.
• the way how the seached query is transferred from e.g. item detail to the search screen is the worst approach I could imagine. Instead of using URL parameters it is using some weird cache which gives no added value, but only makes the app behaviour non-deterministic and hard to debug.

[jterps08]

thanks